Preparing and preserving fibers for pulp-making purposes



Patented Feb. 9, 1926.

UNITED STATES I 1,572,539 PATENT OFFICE,

ELBERT C. LATHROP, 0F PHILADELPHIA, PENNSYLVANIA, AND TREADWAY B. MUN- ROE, 0F FOREST GLEN, MARYLAND; SAID LATHROP ASSIGNOR TO SAID MUNROE.

PREPARING AND.PRESERVING FIBERS FOR PULP MAKING PURPOSES.

No Drawing.

To all whom it may concern:

Be it known that we, ELBERT C. LATHROP and TREADWAY B. MUNROE, citizens of the United States, and residing, respectively, at Philadelphia, in the county of Philadelphia and State of Pennsylvania, and Forest Glen, in the county of Montgomery and State of Maryland, have invented certain new and useful Improvements in Preparing and Preserving Fibers for Pulp-Making Purposes; and we do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to a method of preserving and partially preparing bagasse fibers for pulp making purposes by means of a pasteurizing procedure and' a partial driving off of the moisture therein, and has for its object to provide a process which will be certain in action and more simple to carry out than those heretofore proposed.

With these and other objects in view the invention consists in the novel steps and combinations of steps constituting the process all as will be more fully hereinafter disclosed and particularly pointed out in the claims.

In order that the precise invention may be the more clearly understood it .is said: Bagasse fibers as they leave the sugar mill contain varying, but small amounts of unextracted sugar, together with carbo-hydrate gums not easily soluble in water. The water content of a mass of raw bagasse' is substantially 50%, depending upon the particular actions to which it was subjected before leaving the sugar mill. If the bagasse was immediately dried after leaving the mill very little if any change in the mass will be subsequently brought about by fermenting actions, since it is well known that micro-organisms require Water in order to Application filed June 20, 1924. Serial No. 721,364.

same chemically, neither of which procedures are commercially feasible. These said alcoholic and acetic acid fermentations are confined, however, to a destruction of the sugar content and of the gums present, so that substantially no fiber onother real values of the bagasse material are lost by the same.

These said fermentations are also accompanied by the production of, heat, and by the production of compounds which make more favorable the conditions of growth of other organisms. Of these other organisms there has' been found present in the bagasse, bacteria, trichoderma, monilia, fusarium, aspergillus, penicilium, mucor and other forms under various conditions. Many of these last named organisms ferment the bagasse in a destructive manner, causing a weakening of the fibers or a loss of fibers or of other valuable constituents of the bagasse. If favorable conditions,

such as moisture, temperature,oxygen supply, hydrogen on concentration exists, the growth of one or more of these groups of organisms is increased, thereby causing an increased deterioration of the valuable bagasse constituents.

It is therefore important to find a way of preventing the continued presence of these last named fermentation organisms and to preserve the bagasse from the resulting damage, to the end that substantially no values are lost before the fibers are cooked preparatory to making them into the desired heat insulating board.

It has been observed that these alcoholic and acetic fermentations generate heat in the bagasse when stored in piles and in bales. It has also been found that temperatures of 60 C. to 65 C. are present in the interior of such piles or in the interior of such bales. These temperatures persist for a period of a few days to several months, depending on the conditions of storage and piling. The bagasse fiber and mass of bagasse however has high insulation properties so that such piles and bales, and especially when said bales are in iles, tend to retain the heat for a period 0 several days, weeks, or months depending on the conditions that exist in the bagasse masses. It is also observed during the fermentation accompanying the heating that large volumes of carbon dioxide are formed which pass off. This gas is warm and passes off saturated with water vapor thus aiding. in drying out the pile or'bales' of bagasse.

It is well known that a temperature of substantially 60 C. for a period of time will pasteurize, or will more or less sterilize materials of this kind, thus killing micro-organisms or their spores. The longer thetemperature is maintained the greater will be the sterilization. It has been observed that bales of bagasse subjected to storage, as hereinafter described, are either entirely sterile or have present therein only a few, or a very specialized type of organisms, and that the bagasse fiber has suffered substantially no deterioration. At the same time, due to the high temperature, and ethe fermenting action the fibers have become softened and are therefore more easily refined than are fibers which have not been subjected to fermentation. It results that a less cooking is required preparatory to making said fibers into the desired heat insulating board. Moreover, the b'agasse bales will be found to have been dried out to'as low as 20% moisture content on their interiors; and a still lower moisture content will be observed on the outside of the bales, so that favorable conditions for the growing of the organisms on the surface of the bales'and penetrating to the interior is substantially eliminated.

By following the procedure nowto be outlined which involves the controlling of the mill prior to-baling. As above-stated about.

7 generated therein.

alcoholic and acetic acid fermentations re sulting in the heating up of the bagasse the deleterious fermentations due to other organisms is prevented, and therefore the quality of the bagasse for heat insulating board making purposes is greatly improved.

Although it is to be understood that this invention may be carried out in other ways without departing from the spirit thereof one mannerin which it may be carried out may be stated as follows:

The bagasse is preferably baled into a compacted mass as described in U. S. Patent 1,479,419 issued to T. B. Munroe under date of January 1, 1924:, and entitled Method 56 of preserving bagasse fibers, etc. with the exception that nolime or other chemical is added to the bagasse" as it leaves the sugar moisture remains in thebagasse after baling and a bale is so compacted that very little heat will escape therefrom after it is The bales within the course of a daytof a few days wlll develop the alcoholic and lower fatty acid fermentations. At this time a production of carbon dioxide also begins and the bales heat up on their interiors.

The bales are then disposed into piles of many. hundredor even of several thousand .bales' to .a pile, so that the proportions of bales exposedto the direct weather is smallliable to ta e place. If disposed intoo small piles, however, or with exceedingly large air channels, the heating is apt to be of a duration too short to pasteurize the bagasse.

- During the storage under the above conditions a substantial sterilization takes place,

and the moisture content of the bales is markedly lowered, but particulerly the outsides of the bales are dried out, so that to the touch and sight the said bales appear to be entirely dry. If kept moderately dry, substantially no further fermentation takes place, for the heating up and drying out process destroys the microorganisms which brought about the effective fermentation processes.

It is now necessary to prevent the bales from becoming too wet, and in order to do this the top of the pile should be covered as a necessary precaution. This may be done in any suitable manner, but it is preferred to spread loose bagasse to approximately eight inches deep on top of the pile, a sufiicient venting being provided by vertical air channels adapted to carry off the gases and vapor. But these said vertical vents should be so arranged that substantially no rain can.

run down along the sides of the bales and thus reach the interiors thereof.- The bagasse so sterilized and stored will be found to have suffered substantially no deteriora tion of fiber and the fiber will be found to have so softened that it is more easily cooked and refined preparatory tov making the desired heat insulating board, than is the case with untreated fiber:

From the foregoing it will now be clear. that by subjecting raw bagasse in piles to an alcoholic or acetic acid fermentation under such conditions that the temperature will rise to say 60 0., and maintaining this tem-. perature for a suflicient time the mass ofbagasse will become substantially sterile, and will keep in that state solong as. ,moisture is prevented from. entering the same. It will also be found that the fibers of said ,mass will retain their strength unimpaired,

that they will be softer than untreated fibers, and that they will not require as much cooking and refining in the process of making heat insulating boards as do untreated fibers.

Although the above disclosure has been confined to bagasse fibers, it is to be understood that other analogous fibers can be similarly treated with beneficial results, such for example as the fibers of bamboo, rice straw, cornstalks, etc.

What is claimed is:

1. The process of treating fiber producing materials which consists in subjecting a mass of said material to suitable fermentation under such conditions and for such a time as will cause the heat generated in the interior of the mass to substantially sterilize the same; and preventing injurious quantities of moisture from entering the sterilized .lIlitSS.

2. The process of preserving and treating fiber producing materials preparatory to refining the same, which consists in subjecting said material to a fermenting action for a time sufficient to soften said material and sterilize the mass; and preventing injurious quantities of moisture from entering the sterilized mass.

3. The process of preserving and treating bagasse and analogous fibers which consists in subjecting said fibers in masses to suitable fermentations for times sufficient to soften the same and to generate heat on the interior pf said masses; so piling said masses as will iretain the heat on their interiors for a time sufficient to lessen the moisture contents thereof and to substantially sterilize said masses; and preventing sufficient moisture from entering said mass to destroy said sterilization.

4. The process of preserving bagasse from injurious fermentations, which consists in subjecting the same in masses to a fatty acid fermentation under conditions and for a time sufficient to soften the fibers without weakening the same and also sufficient .to, sterilize through the heat evolved in said masses and thus protect said masses against said injurious fermcntations. v

5. The process of treating fibers suitable for making heat insulating boards, which consists in subjecting a mass of said fibers to a fatty acid fermentation under such conditions as will cause the heat generated in the interior of the mass to. substantially sterilize the same; and preventing injurious quantities of moisture from entering the sterilized mass until it is ready for being subjected to a cooking action. l

6. The process of preserving and treating bagasse and analogous fibers suitable for making heat insulating boards which consists in subjecting said fibers in masses to fatty acid fermentations to soften the same and to generate heat in the interior of the said masses; so piling said masses as will retain the heat in their interiors for a time sufficient to lessen the moisture contents thereof and to substantially sterilize said masses; and preventing suflicient moisture from entering said mass to destroy said sterilization.

tures.

ELBERT O, LATHROP. TREADWAY B. MUNRQE.

In testimony whereof we afiix our signa- 

